Brake



Aug. 27, 1935. 1.. o. WADSWORTH 2,012,647

BRAKE Filed July 27, 1932 3 Shets-Sheet l INVENTOR. FRH/VK LLZ WHDSWHRTH ATTORNEY Aug. 27, 1935. F. L. o. WADSWORTH 2,012,647

, BRAKE Filed July 27, 1932 5 Sheets-Sheet 2 I N V EN TOR. Hmvx' L, [/2 WHUSWRT/i ATTORNEY 4 Aug. 27, 1935. F. L. o. WADSWORTH 2,012,647

BRAKE Filed July 27, 1932 3 Sheets-Sheet 3' Tzg 7 INVENTORQ Hum/x L, [2 MOSHE/Q77) TTORNEY 'Patented Aug. 27} "1935 I l UNITED STATES PATENT" OFFICE BRAKE Frank L. 0. Wadsworth, Pittsburgh, Pa., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation Delaware Application July 1932, Serial No. 625,114 21 Claims. (Cl. 188-78) This invention relates to brakes and more parthe following detailed description when taken in ticularly to vehicle brakes of the internal expandconjunction with the accompanying drawings. ing type having in effect a single anchor and It is expressly understood, however; that the floating friction shoe. drawings are employed for purposes of illustra- The above referred to type of brake comprises tion only and are not designed as a definition of is m general a floating. friction shoe having sepathe limits of the invention, reference being had rable ends adapted to be spread apart by an exfor this purpose to the. appended claims. pending mechanism and an anchor either located In the drawings, wherein similar reference between the shoes in order to engage one shoe characters refer to similar parts throughout the end or the other, depending on the direction of several views:

drum rotation, or else a separate anchor located Figure 1 is a front elevation partly in section of near each separable end of the shoe but for a a single anchor brake having actuating means in similar purpose, as the single anchor. In most accordance with the invention which reacts to of these structures, some difliculty is encountered initially engage a central portion of the lining;

with clicks resulting from the fact that one or Figure 2'is'a front'elevation partly in section 1 5 both ends of the brake shoe leave its or their showing a slightly modified form having a diiIerpoints of anchorage before the shoe actually enent actuating mechanism from that shown in Figgages the brake drum, and the shoe upon engagure 1;.

ing the brake drum suddenly thrusts one of its Figure 3 is a front elevation partly in section ends back into solid anchor engagement. Obviof a single anchor brake wherein a cam, lever, 20

ously should the movement resulting in click be cable, and cable guide are used for initially enexcessive, the servo action of the brake may serigaging a central portion; Y ously amplify the shock and damage the brake Figure 4 is a slightly modified form of Figure 3; or its associated vehicle. To prevent this, mini- Figure 5 is a section through the line 5-5 of mum clearances in brakes are maintained as well Figure 3;

as means provided to resiliently retain one shoe Figure 6 isa front elevation partly in section of end in anchor engagement, usually the end which another modification wherein a toggle actuating takes the forward braking torque, thus disregardmeans is utilized to obtain the desired results; ing the presence of click in reverse operation. and Accordingly, it is an object of this invention Figure 7 is a section through the line I-.-'I of 30 to provide a brake having novel features adapted Figure 6 showing the arrangement of the toggle. to do away with the diiflculties herein above re- Referring to the drawings more in detail there ferred is shown in Figure 1 a brake drum ID, a brake A further object of the invention is the provishoe l2, and a backing plate It carrying a single $1011 of brake having flo tin ic n and anchor l6. Actuating levers l8 and 20 are pivoted 35 wherein both ends retain their anchor engageto the brake shoe l2 at a point 22 diametrically ment until after friction contact with the drum opposite the anchor and extend diametrically has been made. across the'brake-and between the anchor l5 and A still further object is the provision of means the shoe ends 24 and 26. A toggle 28 and cable for engaging a portion of the friction band with 30 extending through the backing plate by means 40 the drum prior to the'spreading of the ends of of a conduit 32 are provided to spread levers or the frictionjband. struts l8 and 20 to actuate the brake. A pair Still another object is the provision of common of springs 34 and 36 are connected between the means for successively engaging a central portion shoe. ends 26 and 24 and suitable hooks 38 and 40- 40 and the end portions of a floating friction shoe. mounted upon the backing plate 'in order to main- A still further object is the provision of means tain or urge the ends of the shoes against the for contacting a central portion of a floating anchor IS.- A third spring 42 is connected bebrake band by reaction of a guide bearing of a tween the pivot 22 and the backing plate and is flexible cable control. adjusted to maintain proper shoe clearante in A further object is the provision of actuating released brake position. .The end Not the brake 5i) means in combination with a brake-having'floatshoe I2 is provided with an adjustable member 52 ing friction means, wherein reaction is utilized to having a pair of slots one of which is indicatedfirst engage acentral portion of the friction lining. at 44 adapted to slide upon the bolts 46 and 48. The above and other novel features ofthe in- In order to adjust the length of the brake shoe vention will appear more fully hereinafter from an eccentric I9 is pivoted upon the bolt 48 and is adapted to engage a shoulder 66 upon the adjustable member 62 so that rotation thereof may produce lengthwise adjustment of the brake shoe.

A slightly different construction embodying the same characteristics as that shown in Figure Lis shown in Figure 2 wherein the usual brake drum I6, the friction shoe 66 and backing plate I4 having an anchor 16, is shown. In order to actuate the structure therein illustrated a pair of levers or struts 62 and 64 are shown pivoted at 66 and 66 to the brake shoe 66 and extending between the shoe ends and the anchor diametri In order to spread the levers, a novel actuating mechanism is used comprising a flexible cable 62 passing through a conduit 64 in the backing plate and secured to a pair of flexible band tension members 66. passing around rollers'66 and secured upon wedge blocks 66 rigidly secured to levers 64 and 62, as shown. It will be readily observed that a pull upon the tension element 62 will cause the rollers 66 encompassed by 'the bands 66 to roll upon the wedge faces of the wedges 66 and thus tend to spread. the struts or levers 62 and 64. .However, in both showings of Figures 1' and 2 the downward'thrust of the spreading force exerted by the toggle of Figure, 1 .and the rollers of Figure 2 will tend to thrust the struts downwardprior to any spreading action as a result of the balance of various springs utilized in the two modifications. This downward' thrust will engage the central portion of the shoe before either end leaves its engagement'with the anchor thus preventing any possibility of click since the initial engagement of the central portion of the friction shoe will determine which shoe end is to leave the anchor when spreading action between the ends begins.

In Figure 3 there is shown a brake having a lever and cam for actuating the same combined with suitable mechanism for deriving the sequence of operation outlined with respect to Figures 1 and 2. Illustrated in Figure 3 are the usual brake drum I6 and friction shoe 32, backing plate I4, and an anchor 34 secured thereto. In order to actuate the brake a floating cam and lever 36 having cam' surfaces 66 and I66 are employed to spread the ends I62 and I64 of the brake shoe. A flexible cable I66 extending through a conduit I66 in the backing plate is secured to the end of the lever 36. In order to adjust the brake for wear a suitable left and right adjusting screw II 6 is provided which may be threaded into the ends of the brake shoe diametrically opposite the anchor. Secured to one of the shoe ends is a bracket I I2 carrying a guide pulley II4 over which the cable I66 passes in engagement therewith. The

bracket may be secured to the other shoe end'as position. The radial springs II6, I26, I22, .and

I24 may be positioned as shown in Figure 5 wherein the backing plate I4 is shown as carrying a guide member I23 through which the end of the spring I22 passes prior to beingsecured to the shoe 62. A suitable clearance adjusting screw I26 may be threaded in the guide I23 and adapted to engage the flange of the shoe 32.

It will be readily observed that in applying tension to the cable I66, guide pulley II4 will be first thrust downwardly causing the adjacent portion of the friction shoe to engage the drum, so that upon-subsequent tension being applied and separation of the shoes about the anchor, one of the shoes will be held in engagement with the anchor by braking torque thus avoiding the possibility of any click.

In Figure 4-aslight modification of the structure of Figure 3 is shown wherein a guide pulley 1 [32 is provided one. bell crank I34 which acts through a resilient spring I36 to engage the brake shoe adjacent thereto. An adjusting mechanism comprising a wedge I36 is adapted to act upon the inclined ends I46 and I42 of the brake shoes to spread the same and make adjustmentsfor wear. Movement of the wedge I36 is accomplished by means of a screw I44 which is carried in the bearing member I46 resiliently centered between the shoes by means of springs I46 and I56 and adjusting nuts I62 and H54. As may be readily seen upon a tension being applied to the cable I66 a rocking action of the bell crank I 34 carrying roller I32 will take place thrusting the friction means in engagement with the brake drum as in Figure 3;

' A further modification for accomplishing the same purpose is shown in Figure 6 wherein a toggle is arranged between the-usual actuating mechanism and a central portion 0115116 friction shoe. As shown, the construction comprises a brake drum I6 and a backing plate I4 carrying an anchor I66 and provided with a floating friction shoe as indicated at I62. A suitable linkage for spreading the ends I64 and I66 of the friction shoe comprises-a link I66 and a hook shaped lever I66 pivoted by a short link I62 to the backconnected to the lever I66 and adapted to be actuated by the toggle I66 as is best shown in Figure 7. A hearing member I 62 is provided in order to carry the thrust of the toggle on the lever I66. The opposite end of the toggle is adapted to radially thrust the friction shoe into engagement with the brake drum and for this purpose the actuating link I 6i and cable I63 are attached to an extension I66 upon the knee of the toggle. Any suitable means as I64 struck up in the backing plate may be used to compensate for the side thrust of the shoe and toggle and guide the same. A suitable adjustable end member I96 is provided on the end I64 of the brake shoe and is adapted to be moved circumferentially with respect to the shoe by the adjustment screw I96 and to be locked in position by the clamping'stud 266. Suitable springs 262, 264, 266, and 266 may be provided to maintain the brake in proper released balance.

In operation, referring to Figures 1 and 2, it will readily be seen that a pull on the operating cable tends to spread the struts against the action of the springs 34 and 36 of Figure 2. These springs are tensioned such that before permitting spreading action the struts will be thrust downward so as to engage a central portion of the friction lining with the drum. In other words,

the springs 32, 36, and 80 are so te'nsioned as to insure and require the reaction of the friction lining in contact with the drum before spreading action of the brake shoes may begin. As a resuit, the central portion of the brake shoe engages the drum first while both shoe ends are in contact with the anchor. One of the shoe ends immediately commences to resist braking torque, and is maintained in anchor engagement thereby throughout the subsequent increase in brakin pressure, and spreading 'of the shoes.

. Similarly in the modifications of Figures 3 and 4 the sequence of operation remains the same. Tension applied to the cable 106 first tends to thrust the guide toward the brake drum since the return spring I is of proper tension to bring this about. In Figure 6, operation of the toggle tends to expand the shoe in the same manner necessarily thrusting the central portion of the brake shoe into drum engagement before extending the springs 202 and 208, the latter of which are of sufilcient tension to force the central portion of the friction means into drum contact before spreading action about the anchor liifmay take place.

, While various embodiments and modifications of the invention have been illustrated and described it is to be understood that the invention is not limited thereto but may be embodied in various mechanical forms. As such changes in construction and arrangement of parts may be made without departing from the spirit of the invention as will be well understood by those skilled in the art, reference will be had to the appended claims for a definition of the limits of the invention.

I claim:

1. A brake comprising a drum, friction means therein having a pair of separable ends, an anchor arranged between said ends, and actuating means adapted to urge said separable ends apart and mechanically connected to a central portion of said friction means to thrust it into drum engagement.

2. A brake comprising a drum, friction means thereinhaving a pair of separable ends, an anchor therebetween, a-spreading means for separatsaid cable bearing upon an intermediate portion of said friction means to derive additional pressure.

4. A brake comprising a drum, friction means therein having a pair of separable ends, ananchor therebetween, actuating mechanism including a tension cable for spreading said ends, said cable bearing upon an intermediate portion of said friction means for initial frictional contact of said portion with said drum.

5. A brake comprising a drum, anchor means and a friction means having separable ends normally anchored, means linked to a central por tion of the friction means for actuating said portion of said friction means into engagement with the drum while retaining said ends normally anchored, and means associated with said actuating means and acting on said ends for subsequently spreading said ends. I

6. A brake comprising a drum, a friction means I therein having separable ends, an anchor therebetween normally in contact therewith, means for spreading said ends, and toggle operating means connected to a central portion of said,

friction means and said spreading means.

7. A brake comprising a drum, friction means therein having separable ends, anchor means therefor, substantially diametrical levers, an end of each pivoted to a central portion of said friction] means and adapted to spread said separable ends,

- and means for exerting a radial thrust toward said pivoted ends and for spreading said levers.

8. A brake comprising a drum, friction means therefor, an anchor intermediate a" pair of separable ends of saidfriction means, actuating means acting directly'on a central portion of said friction means, and said separable ends, and

mechanism to radially thrust said actuating means in the direction of said central portion and actuate the same to spread. said ends.

9. A brake comprising a drum,,friction means having separable ends, anchor means for said ends, and means connected to said ends and to a central portion of the friction means and operable to thrust said central portion of said friction means into drum contact' and spread said separable ends.

10. A brake, a drum, an anchor, a band friction shoe, links pivoted to a central portion of said shoe and extending between the ends of said shoe and the anchor, means for separating said links exerting a radial reaction to first frictionally engage said central portion.

11. A brake comprising a drum, friction means and an anchor, actuating means to engage said brake comprising a flexible tension member, a guide for said member including a roller mounted on the friction means and engaged by the tension member and reacting to create braking pressure.

. 12. A brake comprising a drum, floating friction means having separable ends, anchor means, resilient means urging said ends into anchor engagement during released position, and actuating means including a linkage connected to the ends and to a central portion of the friction means for expanding said friction means and initially contacting a central portion thereof with the drum before disturbing said release position anchor engagement.

13. A brake comprising friction means, links connected to a central portion of said means and engaging the ends of said means, and an actuating device operable to thrust said links lengthwise toward their connection with the friction means and also operable to force the links apart.

14. A brake comprising friction means, links connected to a central portion of said means-and engaging the ends of said means, and an actuating toggle opening downwardly and operable to thrust said links lengthwise toward their connection with the friction means and also operable to force-the links apart.

15. A brake comprising friction means, links connected to a central portion of said means and engaging the ends of said means, and actuating a centrally-located adjustment and a roller mounted thereon, and an applying devicehaving an operating cable-passing over said roller and urging itin a direction to force the friction means radially outward.

18. A brake comprising friction means having a centrally-located roller, and an applying device having an operating cable passing over said roller and urging it in a direction to force the friction means radially outward.

19. A brake compris 8 riction means having a central adjustment, a lever bearing against said adjustment, and applying means acting on the ends of the friction means and also acting on said lever to rock it in a direction to force the central portion of thefriction means radially outward.

' 20. A brake comprising friction means, a pair of members bearing againsta central portion of said friction means, and applying means acting on the ends of the friction means and also acting on and connectedto said members to move them in a direction to force the central portion of the friction means radially outward.

21. App ying means for a brake comprising two pivotally-connected members forming a toggle extending radially of the brake, a tension element extending perpendicular to the plane of the brake and connected to said toggle to straighten it to apply the brake, and auxiliary brake-applying means connected to one member of the toggle and actuated by the reaction thereof.

FRANK L. O. WADSWORTH. 

